Clock



FIG. 1 is a perspective view of a clock showing my new design;

FIG. 2 is a front view of a clock;

FIG. 3 is a rear view of a clock;

FIG. 4 is a right side view, the left side view being substantially a mirror image thereof;

FIG. 5 is a top plan view of a clock; and,

FIG. 6 is a bottom view of a clock. 

The ornamental design for a clock, as shown and described. 